Above pdf file will be translated for aspiring students in aeronautics, control engineering etc. so that in future lay people like me will be able to enjoy planetary scenes and events without worrying about failures.

The overall title is "Looking into the causes of failure and trying to find the right measures to take for the future with respect to the 18th scientific satellite (PLANET-B ) not inserted into Mars orbit as planned" and it is dated 21 May 2004.

This file is very much detailed at 1.1 megabytes and the number of pages is about 40, I think. In addition, I will be translating 3 more files after this particular file. They will be;

1. ISAS file with views and comments on the failure2. Another ISAS file, a newsletter written out in a series of 4 individual letters.3. JAXA file, which is a press release and it is a very concise document with just sufficient details.

Re concise link making I tried a few times, but I simply failed and all the links will be fully pasted out as required.

About this coding business I have been thinking about it for the last three weeks. Simplest would be to experiment. Here, I will switch on my hardware switch to write "1 A" using 16 bits coding. What goes before that is "1 A" with 8 bits coding.

1. 1 A with 8 bits coding: 1 A

2. 1 A with 16 bits coding: １ Ａ

With 2. above, I actually added one space with 16 bits coding and that may complicate this issue, but not by much, I hope...

If you can read them both without any problems, then I can forget about my worries about this, except that there might still be cases where the person(s) who wrote the whole thing may have used the mixture of 8 and 16 bits codings without consistency.

This is not a small matter of concern. On placing mail orders, for example, your order may be rejected. It does happen, here, often...

Its rough title is something like "what Nozomi may have left for the success of future international planetary missions".

This is entirely in accordance with the purpose of my translating relevant files for the advancment of future missions and I am very pleased that I found this particular file for the communities with interest.

Translations will follow shortly. The original file consists of 4 contributions made by the same person and each may take up to a few times of translation. I will not be identifying the name of the person who wrote these pages.

Its rough title is something like "what Nozomi may have left for the success of future international planetary missions".

This is entirely in accordance with the purpose of my translating relevant files for the advancment of future missions and I am very pleased that I found this particular file for the communities with interest.

Translations will follow shortly. The original file consists of 4 contributions made by the same person and each may take up to a few times of translation. I will not be identifying the name of the person who wrote these pages.

P

In what follows I am translating this document chunk by chunk as I see fit for the purpose because there are no page numbers as such.

Nozomi left the Earth on 4 July 1998 and travelled across the solar system for over 5 years carrying signatures of hope from more than 270,000 people. I regret to say that we had to teminate the operation of Nozomi at 20:30 on 9 December 2003 (Tuesday) despite the frantic efforts by the team upon confirmation that we had not been able to fix the faulty portions of the system.

Consequently, we kept sending out a command to Nozomi from 20:45 until 21:23 on the same day in order to reduce the possibility of Nozomi colliding with Mars. As a result, Nozomi passed, on 14 December, the height of about 1000 km from the surface of Mars and left the gravitational field of Mars to continue its journey across the solar system once again.

Nozomi, the first of its kind ever launched by Japan, has encountered all kinds of difficulties over the last 5 years as had been expected, had to terminate her mission within the last few steps from her success.

Granted that Nozomi, as Japan's first planetary mission, was not able to achieve the maturity as is now taken for granted in other areas such as X-ray astronomy and space plasma physics we nevertheless think that the lessons learnt from operating this spacecraft in the frenzies of it all during the last 5 years must be told to the rest of the world so that our future planetary missions will benefit from the difficulties Nozomi encountered.

I believe that it is the duty of our group to do just that. We were endowed with the resources for that purpose. We must reflect upon failures. That is the only way foward. Both US and Soviet Union have sent more than 30 spacecrafts to Mars to date and 20 of them have failed. (Is this really, really true?, I doubt it, P) We will have to learn from failures. That is the only way forward.

Learn from successes, ride over the faults we found, it is not regrets, not masochistic either, at all, and we can only do forward looking investigations for the humanity.

Learn from successes, ride over the faults we found, it is not regrets, not masochistic either, at all, and we can only do forward looking investigations for the humanity.

One chunck after above just before two graphs is as follows.

1．On the subject of engineering aspects

There are 4 Japanese spacecrafts which have left the Earth gravitational fields. The first one is the Halley probes, Sakigake and Suisei launched in 1985, then Nozomi, and Hayabusa which is the latest departing in May 2003. However, of all these, Nozomi is the only one which specifically targetted a planet as its destination.

Given limited human resources and finance, very tight scheduling it has been a very challenging task to try and reach a planet. It has been fun, too, of course, with all those technologies to prove in orbit.

First of all, we had this mission analysis. We have gained quite a lot from trying to trade off an innumerable number of engineering aspects in an effort to obtain the maximum benefit from an optimum flight scenario for Nozomi.

I think we have secured the solid foundation for orbital desine and operation technologies, in addition to the experience gained during the flight of Hiten which was launched in 1990, making use of swing-bys with the Earth and the Moon.

Needless to say that we were all very much encouraged and impressed by the frantic efforts shown by this "Orbit and Mission" team, sacrifysing the period non-stop, from Christmass through to the new year period in the face of fuel depletion in the wake of the Earth swing-by in 1998. The heroic dedication that they showed in coming up with a renewed mission plan was a ray of hope for the Japanese space science and technologies.

End of this chunck and this is followed by schematics. I am unsure as to what I might do about them, yet. P

End of this chunck and this is followed by schematics. I am unsure as to what I might do about them, yet. P

With these two schematics my contributions are minimum and it shouod suffice. The first one on the left is all in English. The second one on the right is more or less self-explanatory. I might add that red is Mars, purple is Nozomi and the green is the Earth. What follows after these graphs is as follows.

Next is the technology for determining the orbit very accurately. We have obtained these technologies and trained ourselves in them from the interactions between the ground based commands and the responses from the spacecraft so tha we now know how we can determine orbits in deep space, line of sight distance, velocity data etc. to put them into an extremely precise dynamical model

Also, autonomous technology. Sometimes, it takes as much as 20 minutes by the radio waves to reach the spacecraft. Therefore, a lot of decisions are left for the spacecraft to make by the onborad computers. We managed to gain a limited amount of insight into the workings of "autonomous decision makings". This experience was put into a maximum use in the case of Hayabusa.

In short, we have obtained a maximum experience from our attempts with perational know-hows and use of relevant communication means to keep communications alive over the distance of more than 3.7 times 10 to the power of 8 km using our 64m diameter dish at Usuda station in central highland area of Japan.

What follows is the chunck immediately following the reference to the deep space antenna located in the high land area in central Japan where my family's mountain cottage happens to be only 10 miles from it!

We have also gained a lot in our attemtps to reduce inertial mass of instruments on board. Planetary exploeres need a lot more energy at launch compared with earth circulating satellites. Electronics, cells, antenna, solar batteries, propulsion systems, all these called for new technologies for reduced mass. We believe that we cleared all these hurdles with Nozomi.

(There is a schematic of Nozomi after this, but it should not be a concern to our colleagues. So, I will skip translation here.)

We had not expected to be involved in such a lengthy operation, including a long cruising phase. Under these circumstances, we had to operate very safely given all kinds of constraints and that meant that a lot of the ground support software had to be turned into AI capable, and that brought to us lots and lots of precious experiences.

All this gave us quite a lot for the operation of Hayabusa and all other future planetary missions. On the other hand, there is one notable point of regret in relation to the valve we had incorporated into the control engine in the wake of the US Mars Observer's bitter experience.

What started Nozomi's agony was the half opening of the shut valve which had been put in the downstream of the reverse flow stop valve in the gas supply line which was meant to pressurise the fuel and oxidiser tanks. Other people's experiences are hard to digest.

We did mean to have learnt from the US experience and we might have installed unneccesary redundancies into our system, or did we? In any event, we will need to spend a lot of time looking into the operational aspects of this and all other relevant pitfalls we might have fallen into.

We also have this short-circuitting issue, following the direct hit by solar particles. There have been many failures to date due to these large scale solar flares. We believe that recent explosions crippled at least a dozen spacecrafts worldwide. We cannot afford to say that ours had been up to the international standard for this kind of troubles. We will have to come up with solutions once and forever.

There are two points here, which we need to examine very carefully.

One is that our original design had been such that a command sent to the short-circuitted portion will automatically bring about an exccessive current, activating a circuit breaker, leading to an immediate loss of the current. However, if you come to think about it this particular breaker had been installed there in the first place to protect the whole circuit. We had the reverse effect of this precaution.

Sure, it may be impossible to take everything into account. However, this reverse effect issue, be it with the valves, or breakers, does and will continue to happen, I think. Many other missions of this kind worldwide have seen this "reverse effects" cropping up almost constantly.

It may well be that there are more than one way of making the maximum use of this experience with the breaker. I can say, at least, that we are that much cleverer now as a result.

Second point of possible arguements is this. This particular circuit had been meant to control both telemetry modulation and the heater for control fuel. Granted that this was due to the utmost need to reduce inertial mass. However, if one of the two had been alive for use we might have found a way to come up with a solution. I am sure that this will be one of the focuses of arguments from now on.

As the first of our planetary missions Nozomi left a lot of issues for us to ponder over and come up with viable solutions for. I am sure that we will be willing to spend time on these issues for many years to come.

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